Benzoquinones
The use of benzoquinones in rubber-based golf ball compositions is known. For example, U.S. Pat. No. 6,339,119 to Ladd et al. discloses a golf ball containing a cover layer and a core layer, where the core layer is molded from a scorch retarding composition comprising a scorch retarding peroxide, an elastomeric polymer, and a crosslinking agent. The scorch retarding peroxide typically contains a free radical scavenger selected from the group consisting of benzoquinones, hydroquinones, phenols, benzaldehydes, cyclohexadiene-1-ones, and mixtures thereof. The amount of the free radical scavenger in the scorch retarding peroxide is preferably from about 0.01 parts to about 2 parts per 100 parts of the peroxide by weight.
U.S. Pat. No. 6,767,940 to Voorheis et al. is directed to a golf ball having a core and cover, particularly to a golf ball core formed from a composition including an elastomeric polymer, a free radical initiator, and at least one stable free radical. The composition can further include one or more free radical scavengers and scorch retarders to increase the scorch time of the elastomeric polymer. Suitable free radical scavengers include benzoquinones; hydroquinones; phenols; benzaldehydes; cyclohexadiene-1-ones; and mixtures thereof.
U.S. Patent Application Publication No. 2007/0213442 to Bulpett et al. discloses the use of benzoquinone-containing rubber compositions in a variety of golf ball layers.
Additional background references include U.S. Pat. No. 6,919,393 to Mano et al., U.S. Pat. No. 6,956,128 to Higuchi et al., U.S. Patent Application Publication No. 2002/0052253 to Fushihara et al., and U.S. Pat. No. 6,488,597 to Iwami et al.
Resilient Cores
The primary source of resilience, as measured by coefficient of restitution (“COR”), in commercially available golf balls is polybutadiene rubber, which is generally used to form all or part of the core. It is known that the resilience of a golf ball core, at a given compression, may be increased by forming a core layer from a rubber composition comprising an organosulfur compound. However, organosulfur compounds can be expensive and can cause processing difficulties.
While the use of benzoquinones in rubber golf ball compositions has been disclosed, there is a need in the industry to broaden the applicability of such compositions to particular golf ball constructions having desirable spin, feel, and distance properties. The present invention provides such golf ball constructions through the use of a dual- or multi-layer core formed from a rubber composition comprising a base rubber and a benzoquinone.